Effects of surfactants or fat solvent on static pressure-volume hysteresis of excised dog lung

¹ University of Buffalo Chronic Disease Research Institute, Buffalo, New York

The static pressure-volume diagram of the lung was studied after the application of surface active agents to the airways of excised lobes of dog lungs. After rinsing of excised air-free lobes with saline or plasma, hysteresis obtained on air inflation and deflation was marked, but it was remarkably reduced after rinsing air-free lobes with surface active agents, 0.5% Tween-20 in saline, 0.5% octyl alcohol in plasma, or with petroleum ether. The reduced hysteresis was accompanied by a diminution in the amount of air remaining in the lobe on return to zero intrabronchial pressure level. The results of the surface tension-area relationship of lung extracts are consistent with those of the pressure-volume characteristics of lungs. These data indicate that the change in slope and position of the deflation curve resulting from fixing surface tension at about 25 dynes/cm, reduces hysteresis, in correspondence with the reduction of the volume of trapped air at zero intrabronchial pressure level.